Another senior former ­commanding officer of the Special Forces Support Group quit as cuts took their toll.

“The sort of defence cuts we have seen have really hollowed out the British armed forces”

General Sir Richard Shirreff

The SAS commander, who currently works in the ­operations department of the Ministry of Defence, was due to attend the High Command and Staff Course.

One senior source said last night: “The Army can’t afford to lose men of his character and experience.

“The tragedy is that he is just one of many SAS officers who are now considering their futures.

“The Army demands a great deal from its best officers and the higher up you go the ­harder the jobs become.

"He, like many of his colleagues, has spent a large proportion of his military career on ­operations.

“But there is a growing view that the sacrifices are no ­longer worth it.

“We are all looking at the costs versus the benefits and for many of us the cost is too great.”

Virtually every part of the armed forces has suffered ­under the defence cuts and the Army will see troop levels fall from around 105,000 to 82,000 by 2015.

Last week it emerged the Army now has only 227 Challenger 2 battle tanks, a fleet smaller than that of France, Germany and Switzerland – a neutral ­country which has not fought a war for more than 150 years.

General Sir Richard Shirreff, the Army’s third most senior officer, has warned: “The sort of defence cuts we have seen have really hollowed out the British armed forces and I think that people need to sit up and recognise that.”